Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting goblet cells
Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus by ciliary action
Location: Nonciliated type lines most of the digestive tract (stomach to rectum) and gallbladder
Ciliated variety lines small bronchi and uterine tubes
Description: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar; cells at the apical surface are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers
Function: Protects underlying tissues in areas subjected to abrasion
Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina
Keratinized variety forms the epidermis of the skin, a dry membrane
Description: Single layer of cells of differing heights, some not reaching the free surface, but all touching the basement membrane; nuclei seen at different levels; may contain goblet cells and bear cilia
Function: Secrete substances, particularly of mucus; propulsion of mucus by ciliary action
Location: Nonciliated type in ducts of large glands, parts of male urethra
Ciliated variety lines the trachea, most of the upper respiratory tract
Simple Squamous Epithelium
Description: Single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epithelia
Function: Allows passage of materials by diffusion and filtration in sites where protection is not important; may secrete lubricating substance
Location: Kidney glomeruli; air sacs of lungs; lining of heart and blood vessels; lining of ventral body cavity
Simple Cuboidal Epithelium
Description: Single layer of cubelike cells with large, spherical central nuclei
Function: Secretion and absorption
Location: Kidney tubules; ducts of small glands; ovary surface
Simple Columnar Epithelium
Description: Single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting goblet cells
Function: Absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus by ciliary action
Location: Nonciliated type lines most of the digestive tract (stomach to rectum) and gallbladder
Ciliated variety lines small bronchi and uterine tubes
Stratified Squamous Epithelium
Description: Thick membrane composed of several cell layers; basal cells are cuboidal or columnar; cells at the apical surface are flattened (squamous); in the keratinized type, the surface cells are full of keratin and dead; basal cells are active in mitosis and produce the cells of the more superficial layers
Function: Protects underlying tissues in areas subjected to abrasion
Location: Nonkeratinized type forms the moist linings of the esophagus, mouth, and vagina
Keratinized variety forms the epidermis of the skin, a dry membrane
Stratified Cuboidal Epithelium
Description: Stratified cuboidal epithelia is an uncommon kind of epithelial tissue made up of cuboidally shaped cells layered in layers.
Function: Protection
Location: Forms largest ducts of sweat glands, mammary gland, and salivary glands
Stratified Columnar Epithelium
Description: Stratified columnar epithelium is an uncommon kind of epithelial tissue made up of numerous layers of column-shaped cells.
Function: Protection
Location: Mammary gland ducts, larynx, male urethra
Pseudostratified Columnar Epithelium
Description: Single layer of cells of differing heights, some not reaching the free surface, but all touching the basement membrane; nuclei seen at different levels; may contain goblet cells and bear cilia
Function: Secrete substances, particularly of mucus; propulsion of mucus by ciliary action
Location: Nonciliated type in ducts of large glands, parts of male urethra
Ciliated variety lines the trachea, most of the upper respiratory tract
Transitional Epithelium
Description: Basal cells cuboidal or columnar; surface cells dome-shaped or squamous like, depending on how much the organ is stretched
Function: Stretches readily and permits distension of urinary organ by stored urine
Location: Lines the ureters, urinary bladder, and part of the urethra